This invention relates to a process for minimizing waste during processing of a length of stock, including, for example, structural steel shapes, such as I-beam, channel, angle iron, and bar stock, into one or more shorter length segments. More specifically, the process increases the amount of material available for forming smaller usable segments.
In conventional xe2x80x9ccut to lengthxe2x80x9d structural beam fabrication shops employing a steel fabrication line, beams are typically automatically conveyed through an assembly of punch presses for punching holes in the beams and a shearing device for severing the beams into multiple, smaller (i.e., shorter) length segments. One example of beams that are processed in this manner has a central web and two parallel flanges, where each flange is arranged at opposite ends of the web. Such beams are typically designated as I-beams, wide flange beams, light beams, and American standard beams. When such beams are erected in structures, the ends of the beams and/or other portions of the beams are typically connected together with bolts. The bolts are received in holes provided in the webs and flanges of the beams.
One conventional method for providing the holes in a beam is to punch the holes with one or more conventional punch presses. xe2x80x9cWebxe2x80x9d punch presses are used to provide holes in the beam web, and xe2x80x9cflangexe2x80x9d punch presses are used to provide holes in the beam flanges. Such punch presses may have conventional designs well-known to those skilled in the art. Various designs are disclosed in U.S. Pat. Nos. 4,631,996, 3,722,337, and 3,720,125.
One conventional method for forming one or more shorter segments from a length of stock is to sever the shorter segments from the length of stock with a shearing apparatus. Such shearing apparatus may have conventional designs well-known to those skilled in the art. One example of a possible design is disclosed in U.S. Pat. No. 5,394,782.
A family of models of commercially successful structural beam punch and shear combination systems is marketed in the United States of America by Peddinghaus Corporation, 300 North Washington Avenue, Bradley, Ill. 60915 U.S.A. under the trade name xe2x80x9cAnglemasterxe2x80x9d and can be used as part of a structural steel fabrication line. The Peddinghaus brochure 08/94 AFCPS describes the Model AFCPS-623-K, and the Peddinghaus brochure 07/88 ASP describes the Model AFPS 623.
Generally, for xe2x80x9ccut to lengthxe2x80x9d fabrication lines, the operator starts with raw stock of a standard fixed length. In connection with processing a length of stock including structural steel shapes, such as I-beam, channel, angle iron, and bar stock, the raw stock commonly comes in a fixed length of 40 feet. Other standard fixed lengths can often also be available, wherein a maximum standard fixed length of 60 feet is common. From the standard fixed lengths of raw stock, shorter beam segments of desirable length can be produced.
In order to minimize waste, during production of the shorter length beams from the raw stock, operators of cut-to-length lines look to their production requirements including the quantity and corresponding lengths of the shorter segments required to complete the job order. An operator then plans the production of the parts bearing in mind the standard length of raw stock that the operator is working with, and attempts to organize production of the parts to maximize use of the raw stock, thereby minimizing waste.
As each useable segment is severed, the length of raw stock remaining for forming further shorter useable segments is correspondingly reduced. At some point the remaining length of raw stock will be too short to produce any further useable segments. The length of raw stock remaining after all of the shorter usable segments have been severed is generally referred to as the remnant, and is often discarded as scrap.
Prior processes for producing multiple shorter segments from a longer length of raw stock have typically required a minimum amount of scrap, which can not be processed or used in forming the usable shorter segments. One reason for this has been the result of certain physical limitations of the fabrication line, where a minimum length of material at the trailing end of the raw stock is required for handling purposes. Consequently, many operators, when determining the length of material available for forming shorter segments, automatically deduct from the starting length of raw stock a length equivalent to the minimum handling length. This insures a length of raw stock is always available for handling purposes at the end of the length of raw stock as each shorter usable segment is severed.
A further difficulty in determining the length of material available for forming shorter segments corresponds to the fact that the actual starting length of the raw stock can vary within certain tolerances. In at least one example the actual starting length for at least one source of 40-foot I-beam stock, when received from the mill, can vary by as much as a quarter of an inch under or as much as three-quarters of an inch over. As a result, when planning the formation of the shorter usable segments from the longer length of raw stock, the possible tolerances need to be taken into consideration.
A still further factor which may not always be able to be accurately anticipated corresponds to losses during processing. Each of the resulting shorter cut-to-length segments can further have a tolerance plus or minus of up to one-sixteenth of an inch.
Consequently, when planning the shorter usable segments to be produced from the corresponding lengths of raw stock, prior processing methods have generally identified the length of material available for forming shorter usable segments by deducting from the overall length of raw stock an amount equal to or greater than the minimum handling length. By doing this, it was assured that an amount equal to the minimum handling length was available at the end of processing for handling purposes by the fabrication line.
For a fabrication line having a minimum handling length of eight inches and working with raw stock having a starting length of approximately forty feet, after subtracting the minimum handling length from the overall length of raw stock, the length of material available for forming smaller usable segments would be approximately thirty-nine feet, four inches.
Almost always the individual shorter segments that are needed will not add up exactly to the length of the available material, which length, in the above noted example, is thirty-nine feet, four inches. Consequently, the unused portion of the available length of material will be added as scrap to the already reserved eight inches of material corresponding to the minimal handling length. In prior processes, it was frequently observed that if the amount of material corresponding to the minimum handling length had been available for use, a further usable segment could have been formed.
In view of the above-discussed disadvantages of the prior art processing, it would be beneficial to develop a process which would maximize the amount of material available for forming the shorter usable segments, thereby minimizing the waste during processing of a length of stock.
The present invention provides a novel process for minimizing waste during processing of a length of stock into one or more shorter usable segments.
In at least one aspect of the invention, the process is performed in a system including a processing path along which the length of stock having a leading end and a trailing end travels, and a severing station located along the processing path for severing shorter usable segments from the length of stock. The system typically has a minimum handling length.
The process provides for defining one or more shorter usable segments having an aggregate length, plus any processing loss, which is less than or equal to the length of stock. Furthermore, the one or more shorter usable segments are defined so as to provide at least one shorter usable segment having a length greater than the minimum handling length. The shorter usable segments are then mapped onto the length of stock so as to locate the at least one shorter usable segment having a length greater than the minimum handling length as the last segment at the trailing end of the length of stock. The length of stock is then advanced and the segments are severed, seriatim, therefrom.
According to one aspect of the invention, a process is provided where the difference between the sum of the lengths of the shorter usable segments and the length of the length of stock corresponds to a remnant section. When the length of the remnant section is less than the minimum handling length, the remnant section is mapped at a position other than the last segment.
According to another aspect of the invention, the remnant section is mapped as the next to last segment.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention, from the claims, and from the accompanying drawings.